Man-made filament spinneret and extruder head

ABSTRACT

A SPINNERET FOR USE IN EXTRUSION OF MAN-MADE FIBERS AND A NOVEL EXTRUDER HEAD EQUIPPED WITH THE SPINNERET. THE SPINNERET IS RECTANGULAR AND ARCUATE ALONG ITS WIDTH WITH THE MARGINAL EDGES OF THE SPINNERET OF SUBSTANTIALLY THE SAME ARCUATE CONDIGUATION AS THE SPINNERET FACE THROUGH   OUT. THE SPINNERET IS ADAPTED TO BE CLAMPED TO A MATING ARCUATE MARGINAL PORTION OF THE EXTRUDER HEAD TO THEREBY ASSURE AN IMPERVIOUS CONNECTION BETWEEN THE HEAD AND THE SPINNERET.

June 6, 1972 C GAUTHlER ETAL MAN-MADE FILAMENT SPINNERET AND EXTRUDER HEAD Filed Aug. 21, 1969 2 Sheets-Sheet l INVESTORS 2 CHARLES GAUTHIER i JEAN-MR@` V/INCEN-r a /4 Y, .X y lvi BY f .noksgs June 6, 1972 C. GAUTHlER EI'AL 3,667,886

MAN-MADE FILAMENT SPINNERET AND EXTRUDER HEAD Filed Aug. 2l, 1969 2 Sheets-Sheet 2 Hfrnw/UHH mwnnnn HHHIHIHUH lillllllllllm! 'ililllrmlm immuun!!! IULIUULM umm-UHU INVENTORS CHARLES GAUTHIER JEAN-MARIE VINCENT Y im Ew@ ATTORNE Unitedv States Patent Oliice Patented June 6, 1972 3,667,886 MAN-MADE FILAMENT SPINNERET AND EXTRUDER HEAD Charles Gauthier, Lyon, and Jean-Marie Vincent, Le

Coteau, France, assignors to CTA-Compagnie Industrielle de Textiles Artiiciels et Synthetiques, Paris, France Filed Aug. 21, 1969, Ser. No. 851,800 Claims priority, application France, Aug. 21, 1968, 163,686 Int. Cl. D01d 3/00 U.S. Cl. 425-192 7 Claims ABSTRACT F THE DISCLOSURE A spinneret for use in extrusion of man-made bers and a novel extruder head equipped with th'e spinneret. The spinneret is rectangular and arcuate along its width with the marginal edges of the spinneret of substantially the same arcuate configuration as the spinneret face throughout. The spinneret is adapted to be clamped to a mating arcuate marginal portion of the extruder head to thereby assure an impervious connection between the head and the spinneret.

This invention relates to molding devices and particularly filament forming devices including an extruder head spinneret.

The art of man-made filament forming is highly developed and extreme competition exists among the members of the industry. Accordingly, it is a constant objective of those working in the field of filament forming to produce filaments at the lowest possible cost. One manner in which to reduce the cost of man-made filaments is to provide equipment which is more efficient and can be manufactured at greater economy.

Considerable effort has been directed to producing larger spinnerets that can take the pressure required to extrude uniform filaments without deformation of the spinneret or detriment to the quality of the extruded filaments. It has been attempted to employ large rectangular spinnerets so that a greater number of filaments may be extruded from each device, but such rectangular spinnerets have not been generally accepted for a number of reasons, particularly the fact that such spinnerets have been expensive to manufacture and tend to produce an inferior filament due to deformation under the pressure used to extrude the filaments.

Large rectangular spinnerets are known which have the form of a pan, the fiat rectangular bottom being edged by perpendicular walls. These walls in turn present a collar or peripheral edge disposed in a plane parallel to that of the bottom and serving as means for fixing the spinneret to the extruder head.

These spinnerets are often made of a ductile material which may become deformed by the stresses exerted through the pressure of a pump or other device forcing the material to be extruded through the device. Moreover, the cost of these spinnerets is relatively high, particularly when one considers that a major part of the metal, name ly the walls and marginal portions surrounding and perforated zone, are not perforated and thus the eiiiciency of the device is reduced when compared to other spinneret forms wherein the major portion of the metal forming the spinneret is perforated.

The present invention is the result of continuing industry efforts directed at producing a spinneret at reduced cost and greater efliciency. e

The primary object of the present invention is to overcome the disadvantages of prior art rectangular spinnerets.

Another object of this invention is to provide a rectangular spinneret in which a major portion of the plate forming the material is perforated and only a very small portion of the plate about its peripheral edge is provided for attaching the spinneret to the extruder head.

Still another object of this invention is to provide a spinneret which may -be easily constructed and readily attached to the extruder head.

A still further object of this invention is to provide an extruder head having an opening with arcuate portions along the periphery thereof for mating with the arcuate marginal edge of the spinneret and an arcuate clamping member for mating with the marginal edges of the spinneret and clamping them to the extruder head.

Yet another object of this invention is to provide an extruder head which may be simply constructed by employing an annular chamber with a rectangular portion thereof being open so that the extruder head presents an arcuate opening for the spinneret to be attached thereto.

Only a few of the objects have been stated, others will become apparent to those of ordinary skill in the art.

By way of brief description, the present invention includes a spinneret in the form of metallic foil whose central perforated zone is surrounded by a peripheral zone which may be affixed to the opening of the extruder head in a fluid-tight relationship, and characterized in that in any area of the spinneret, the major part at least of the peripheral zone presents substantially the same curvature as the perforated zone adjacent thereto.

A thin rectangular metal plate constitutes the base stock for the spinneret of the present invention. The plate is of a thickness at least ten times less than the width of the plate and preferably 20 to several hundred times less than this width. In constructing the spinneret, the metal plate is bent in one direction, preferably the width of the plate such that in looking at a cross-section taken along a line perpendicular to the major dimension of the rectangular plate, the plate will have an arcuate configuration. The plate may be bent in the length-wise direction, but this requires a larger extruding head and is less preferable. Further, f desired, the plate may be bulged, i.e., presenting a curve in more than one direction, but this configuration is less preferable since it increases the manufacturing costs of the extruder head and the spinneret. The peripheral zone of the spinneret which frames the perforated zone is disposed substantially in the plane or on the curved surface, or approximately in the plane or curved surface of the perforated portion of the spinneret, Without forming an angle or significant change of direction with reference to the perforated surface.

Such a spinneret is easier to produce than spinnerets of the pan shaped construction of the prior art which represent the basic rectangular form of spinneret employed and available in industry today. Such prior are pan shaped spinnerets require a deep impression in forming the walls surrounding the fiat bottom portion, whereas the spinneret of the present invention requires a slight impression or bending at the very most. Thus, the cold hardening of these angular shaped zones that are deeply impressed is avoided, and at all points a homogeneous metal is maintained, allowing excellent regularity of punching the spinning orifices.

The simple form of the spinneret briefly discussed above, lends itself very readily to the production of large spinnerets, especially those in the form of bands that are equal to or greater than a meter in length. Such spinnerets allow production of a sheet of filaments with a single spinneret, which clearly improves the homogeneity and appearance of such a sheet. According to a preferred embodiment of the invention, the band which comprises the spinneret is bent along its smaller dimension, thus assuming the form of a gutter. In operation, the filaments are extruded from the convex side of the spinneret, perpendicularly thereto, and separated as they issue from the spinneret to thereby enhance penetration of the coagulation fluids. drying or cooling uids, etc., depending upon the particular spinning process employed.

The spinneret is held in a working position preferably by gripping the peripheral zone between two jaws near the perforated zone, with the peripheral zone being merely an extension of the perforated zone.

Thus, the peripheral zone of a spinneret can be reduced significantly, this reduction in the peripheral zone being made possible by the fact that the plate from which the spinneret is made is completely homogeneous, the metal of the spinneret not having been weakened by the sharp angular deformation of the edge portions as has been required with the prior art rectangular spinnerets. Thus, according to the present invention, it is possible to spin accurately at a given pressure with a thinner, less expensive spinneret than those conventionally used, the cost savings in constructing the spinneret resulting from the ability to use a lighter weight metal and the ease with which the orifices of a thin foil may be pierced.

Advantageously the marginal area of the spinneret is provided with a continuous groove that forms a closed loop around the perforated area. This groove is adapted to mate with a corresponding configuration of the spinneret support, or extruder head, possibly in the form of a bead, which facilitates positioning of the spinneret. This corresponding configuration can be made as a sealing joint of suitable for-m if desired.

By employing the concept of the present invention, the spinneret may be made of a metal or metal alloy that lends itself to ease in piercing of the spinning orifices and which preferably can be hardened to ensure longer life for the spinneret. Piercing of the orifices is preferably done by punching, in any pattern desired, which pattern will form the perforated area of the spinneret surrounded by the imperforate marginal area. Since the present invention permits construction of a spinneret from thinner foils or metals, the piercing operation is greatly facilitated since the punch will not have to travel through any considerable thickness and the uniformity of each punch or opening can be maintained to a closer tolerance.

The present invention also concerns an extruder head equipped with the spinneret of the invention. The head comprises a hollow body with a feed orifice for the composition that is to be spun and an extrusion orifice as well as means for setting the spinnert in place before the extruder opening.

The spinnert can be applied to the extruder head by a tightening cover against the opening, in direct contact with the edge of the opening, or with an intermediate plate. In any event, the ele-ments with which the spinneret is in contact along its peripheral zone have a form that corresponds in shape and contour to that of the peripheral area so that the spinneret is not substantially deformed in the course of assembly. Preferably, a sealing joint is used to connect the spinneret to the extruder head, but any equivalent means may be employed to secure the spinneret of the invention to an extruder head.

Inside the hollow body of the extruder head, there may be provided a mixing element, a divider or filter or possibly an element which can modify the temperature of the spinning composition, to adjust it to its optimum value for extrusion.

Several of the salutory features of this invention have 'been discussed. Other features and a better understanding of the true nature and scope of the invention will become apparent to those of ordinary skill in the related art when consideration is given to the following detailed `4 description of a preferred embodiment, which is set forth as exemplary, and when taken in conjunction with the accompanying drawings wherein:

FIG. 1, illustrates in perspective and partially in crosssection one embodiment of the invention;

FIG. 2, illustrates in cross-section the form of the spinneret after its assembly into the extruder head of the invention;

FIG. 3, illustrates in plan view the spinneret of the invention; and

FIG. 4, illustrates a second preferred embodiment of the present invention.

Referring to FIG. 1, the extruder head comprises a hollow body 1, which is shown as rectangular in crosssection but any desired cross-sectional shape is permissible, the hollow 'body being connected to a feed passage 2 for receiving the spinning compostion from a pumping station (not shown). A rectangular opening 3, which is the production model is mm. long and 46 mm. wide, is provided in one face of the hollow body 1 symmetrical about the axis of the feed passage.

The hollow body 1 is provided with flanges 4 extending outwardly from the opening 3. A positioning offset 5 is provided in the hollow body at the opening 3 with the offset arranged to receive a distributor 7, which is shown in the form of a iiat perforated plate allowing correct distribution of a spinning composition passing through the extruder head.

A tightening plate 6 is provided having facing offsets 8 which mate with the offsets '5 to provide a receiving channel for the periphery of the distributor 7 when the plate 5 is assembled in its facing position with the flange 4. The plate 6 has a flange 9 which mates with the flange 4 and the flanges 4 and 9 have openings 10 and 11, respectively, which receive a number of bolts therethrough for assembling the extruder head in its iiuid tight relation.

Cover 12, having openings 13 therethrough is provided to overlay the plate 6 and its integral flange 4 in mating relation so that the openings 13 are in axial alignment with the openings 10 and 11 when the extruder head is assembled. The cover 12 may be counterbored as at 14 to provide recesses for the head of the bolts 15 which secure the extruder head in assembled relation.

The shape of the mating surfaces of the plate 6 and cover 12 is extremely important. The surface 16 of the plate 6 and the surface 1.7 of the cover 12 are arcuate and have the same radius of curvature as the radius of curvature of the gutter shaped spinneret 20. Channels Z1 are also provided in the surfaces 16 and 17 to carry a sealing member which assures the uid tight assembly of the spinneret with the extruder head.

This shape of the mating surfaces of the plate 6 and cover 12 is extremely important since when the spinneret 20 is placed over the extension of the opening 3 as formed by the plate 6, the tightening of the cover 12 tends lightly to separate the longitudinal edges of the spinneret to provide slight pretensioning which reduces the risk of deformation of the spinneret when it is subjected to the spinning pressure. This important feature is a result of the arcuate shape of the surfaces 116 and 17 and the fact that the bolts 1-5 have their longitudinal axis extending obliquely to the plane of the marginal edge of the spinneret so that tightening of the bolt 15 produces this extension of the spinneret 20 over the surfaces 16 and 17.

Referring now to FIG. 2, the spinneret 20 is shown in more detail. The perforated portion of the spinneret is indicated generally at 22 with the marginal edges being shown at 23. As can be readily seen, the perforated portion is substantially larger than the marginal areas so that the marginal areas 23 may be held at a minimum to reduce cost in production of a spinneret of the present invention. Within the marginal areas 23 of the spinneret is formed a semicircular channel 24 which is designed to fit about the sealing member 25.

In constructing the device, it is not necessary to produce any sharp angular bends in the spinneret since the channel may be smoothly formed and tightened down over the sealing member 25 which is preferably constructed of stainless steel, whereby the cover 12 securely fastens the spinneret 20 to the extruder head in a uid tight relation.

As can be clearly seen from IFIG. 2, the radius of curvature of the perforated area 22 and the marginal area 23 is substantially the same which avoids any weakening of the spinneret during its manufacture or use.

The spinneret 20 shown in FIGS. l and 2 is constructed with a radius of curvature of 50 mm. and a length 175 mm. and a width of 65 mm. The perforated zone is a rectangle of 48.4 x 1159 mm. centrally located within the unit so as to provide an unperforated peripheral area having a substantially constant width of approximately 8 mm. This spinneret is made of an alloy of 93 platinum, 4% gold and 3% rhodium, with a substantially uniform thickness of .26 mm. It has 90,000 perforations of cylindrical configuration with a diameter of approximately .08 mm. The perforations may be distributed in any desired pattern and in the working device illustrated perforations are in rolls parallel to the width direction of the spinneret.

With this spinneret, it is possible, for example, to extrude at a rate of 316 =kg. per hour, a solution of 19.6% dry polyacrylonitrile in dimethylformamide, into a 40% dimethylformamide coagulating bath, 90,000 continuous filaments whose titer after drawing and retraction is 3.3 dtex. The immersion length of the sheet in the coagulating bath is approximately 80 cm. The liquid of the bath circulates around the spinneret and penetrates very regularly into the extruded sheets of filaments. No difference of characteristics is noted between filaments formed at the center and those formed at the spinneret periphery and all are of good strength.

Another embodiment of the spinneret which has been constructed and proven to be extremely efficient is that illustrated in FIG. 3. The spinneret shown is a rectangular foil 832 x 80 mm. and having a thickness of .26 mm. The spinneret is bent along its width so that a line in the widthwise direction taken at any point along the length of the device would be in the same plane as any other widthwise line, while lines taken on the device parallel to the lengthwise direction are not in the same plane as other lines taken along the lengthwise direction. The bend forms a cylindrical spinneret With a 50 mm. radius of curvature. The perforated area of the spinneret has some 450,000 apertures distributed in 5 rectangular zones which are indicated generally at 30. Each zone contains 90,000 holes separated by an imperforate strip 31 which is constructed 15 mm. wide. Each rectangular zone measures 148 x 60 mm. with the perforations of each of the rectangular zones being arranged in strips with several rows of perforations in each strip. This construction of a spinneret in accordance with the present invention enables one to produce very economically and efficiently a tremendous number of man-made filaments without undue strain on the equipment and thus the filaments can be produced at a considerable saving of time and expense.

Another preferred embodiment of the invention is illustrated in FIG. 4. The body of this embodiment is indicated generally at 1', but the body of this extruder head is circular in cross-section as opposed to the rectangular body of the illustration of FIG. 11. The distributor 7 of the embodiment of FIG. 4 is circular and has slots passing radially through at least an arcuate portion of the distributor 7 and extending in a direction parallel to the axis of the body.

The body 1 is provided with an opening 3 which is rectangular in plan view, but arcuate in cross-section as is clearly seen from the view of FIG. 4. The thickness of the body 1 results in the opening 3 forming a passage of basically pie-shaped configuration when the body is viewed in cross-section. Along the outer portion of the body 1' is provided the spinneret 20 which is arcuate in cross-section as previously described in connection with the extruder head of iFIG. l. Ihe spinneret again has the channel 24 which fits over the sealing member 25 framing the opening of the body 1. The cover 12 is arcuate in cross-section and mates with the arcuate form of the body and the spinneret. The peripheral portion of the cover has openings for receiving the attaching bolts 15 which are tightened down into the tapped and threaded holes extending about the periphery of the opening 3 in the body 1. A heater 40 may be provided interior of the hollow body and the body may be insulated about a substantial portion thereof by a cover 41 enclosing insulation 32. A liquid may be circulated through the chamber formed by the insulation 32 in order to assist incontrolling the temperature of the composition extruded through the device.

This embodiment of the invention is extremely simple to manufacture since it may be constructed from available piping and the dimensions of the piping maintained in close tolerance so that the members of the assembly will fit in tight telescoping relation.

The description as set forth in the specification illustrates the use of the spinneret according to the present invention for production of polyacrylonitrile filaments. It will be recognized, however, that the present invention may be used, with various modifications that will become apparent to those skilled in the related art, for spinning of compositions with a base of any other kind of polymer, e.g., viscose, cellulose acetate, polyvinyl chloride, polyamide, polyester, etc.

Having described the preferred embodiments of the invention, what is claimed is:

1. A spinneret of rectangular shape having a substantially rectangular perforated zone located centrally in the spinneret with a substantially imperforated zone framing the perforated zone, the Width of said imperforated zone being substantially less than the width of said perforated zone and said spinneret being curved about its longitudinal axis to have a gutter-like shape with a substantially constant curvature throughout, said imperforated zone having substantially the same curvature as the adjacent portions of said perforated zone.

2. A spinneret as defined in claim 1 wherein said imperforated zone has a rib therein which is at a substantilly constant distance from said perforated zone and extends continuously around said perforated zone.

3. A spinneret as defined in claim 2 wherein said rib has a semi-circular shape in cross-section.

4. In combination, an extruder head having a hollow body portion, means forming a feed passage to said hollo-w body, a face for said hollow body having a substantially rectangular opening, a tightening plate engaging said face around said opening and having a surface with an arcuate configuration of substantially constant curvature extending completely around said opening, and a cover of rectangular cross section having a surface mating with said arcuate surface of said tightening plate, said tightening plate and said cover having openings aligned with said rectangular opening in said hollow body; an arcuate spinneret positioned between said tightening plate and said cover and having a curvature substantially that of said mating surfaces of said tightening plate and said cover; and means rigidly securing said arcuate spinneret between said cover and said tightening plate.

5. The combination as defined in claim 4 wherein said mating surfaces include channels forming a seal receiving opening framing said opening in said body and said spinneret has a sealing protrusion mating with said channels.

6. The combination as recited in claim 5 wherein fsaid protrusion defines a peripheral rib on one side of said spinneret and a peripheral recess on the other side of said spinneret and further comprising a sealing member nal axis thereof.

References Cited UNITED STATES PATENTS 1,942,632 1/ 1934 Lwen 18-8 l 1,980,234 11/1934 Taylor 18-8 SS 8 3,344,472 10/ 1967 Kitajima et al. 18-8 SC 3,460,199 8/ 1969 Heckrotte et al 18--8 SC ROBERT D. BALDWIN, Primary Examiner 5 M. 0, SUTTON, Assistant Examiner U.S. C1. X.R. 

